A fire hydrant is one of the most easily accessible elements of a regional potable water distribution system. If improperly used as an entry point for the accidental or intentional introduction of significant amounts of a toxic Chemical, Biological or Radiological (CBR) agent into the potable water distribution system, it can be readily converted to an instrument of illness, death, and destruction. Such an introduction of a toxic agent not only compromises the safety of an entire regional potable water supply system, it can even affect its future use, such as where significant affected portions of the piping system must be replaced.
Fire hydrants are connected directly to a municipal potable water supply system via a lateral pipe. The lateral pipe is in-turn connected to an entire regional potable water distribution system. Obviously, the primary use of a fire hydrant is to enable firefighters to connect their hoses to the municipal water supply system so as to extinguish a fire. Fire hydrant valves are not designed to throttle the water flow; rather, they are designed to be operated in either a full-on or a full-off setting.
In addition, a conventional hydrant's main valve is occasionally exposed to large suspended solids, such as pebbles. This exposure, which is caused by deterioration of the pipes in the water conveyance system, prevents the hydrants main valve seal from properly sealing, i.e., making compressive contact with the hydrant's seal ring and ceasing all flow. These design and operational problems are well known, and can occasionally cause costly site damage.
For example, Fire Hydrant Maintenance (Kennedy Valve Company), A 4.15, at p. 1 states that “[t]he most common maintenance need relates to obstructions in the seating area and resulting damage to the main valve. This is detectable by continued flow with the hydrant in the closed position.” Further, at p. 2, the “[f]unction of the drain valve system needs to be checked for proper operation. There are two primary issues that can cause a need for related maintenance, 1) Hydrant barrel fails to drain after use—which subjects it to freeze damage, and 2) During full open hydrant operation, continuous discharge of water is taking place—which can undermine support for the installation.”
Additionally, as described in the National Drinking Water Clearing House Manual, How to Begin an Operation and Maintenance Program (University of West Virginia, 2009), at 2: “Dry-barrel hydrants should always be opened fully because the drain mechanism operates with the main valve. A partially opened hydrant can cause water to be forced out through the drains and cause erosion around the base of the hydrant.”
The current and conventional remedy to these problems is frequent and costly field inspections, maintenance and repairs.
It is well known that use of a fire hydrant in a partially-open configuration can result in considerable flow directly into the soil surrounding the hydrant, which, over time, can cause severe scouring. Moreover, the fact that either a hose with a closed nozzle valve, a fire truck connection, or a closed gate valve is generally attached to the hydrant prior to opening the hydrant's main valve, can further exacerbate this problem.
In order to prevent casual use or misuse, all hydrants require special tools to be opened. This is usually a large wrench with a pentagon-shaped socket. Vandals occasionally cause monetary damage by wasting water when they open a fire hydrant. Such vandalism can reduce municipal water pressure, and can create a potential local backflow problem due to concomitant uncontrolled and sustained reduction in system water pressure. Ultimately, this can impair firefighters' efforts to extinguish fires. Additionally, in most areas of the United States, contractors who need temporary water can purchase permits to use fire hydrants. Such a permit generally requires a hydrant meter, a gate valve and sometimes a clapper valve to prevent backflow into the hydrant.
Generally, municipal service vehicles, such as tank trucks and street sweepers, are permitted to use fire hydrants to fill their water tanks. Similarly, sewer maintenance vehicles frequently require water to flush out sewer lines, which is accomplished by filling their tanks from a nearby hydrant. Unauthorized entities who gain access to this type of mobile tanker, which can contain, for example, 5000-8000 gallons of liquid, can easily introduce a significant quantity of dangerous CBR agents into a water system by injection into a hydrant's discharge ports. Such a successful injection can be accomplished by simply increasing the pressure of the liquid in the tanker so that it is greater than the pressure in the municipal water supply distribution system that provides water to the fire hydrant. Less likely, although possible, is the injection of a contaminant through the external dry barrel hydrant drain holes using a collar. It is noted in this context, that if toxic radiological contaminants were to be injected into the piping system, the result could be catastrophic, inasmuch as cleaning or removing such contamination can require the complete replacement of the entire regional water supply pipe distribution system, as well as potable water supply pipes in those buildings that were subjected to the radiologically contaminated water.
Many of the aforementioned public health and safety concerns were clearly characterized in Ernest Lory, Stephen Cannon, Vincent Hock, Vicki VanBlaricum and Sondra Cooper, POTABLE WATER CBR CONTAMINATION AND COUNTERMEASURES (Naval Facilities Engineering Service Center, 2006). Quoting from the authors' general introductory comments:                This paper provides information on the potential threat to a building's domestic and potable water supplies from CBR agents that could potentially be used by terrorists (taking into consideration they would likely use low-technologies or agents most readily available). People, both mission critical and the general population, are the most commonly targeted assets of aggressors using CBR agents. CBR agent threats can come from wartime or terrorist attacks or accidental or intentional (sabotage) industrial chemical releases. It is generally assumed that the catastrophic consequences of a CBR terrorist attack or industrial release would be short in duration, perhaps lasting only a few hours. However, (emphasis added) decontaminating a potable water distribution system of a CB agent may take several days. Radioactive material releases can contaminate a water distribution system making it unusable for months or even years creating an enormous health impact. If a small military camp was targeted, the camp could be moved, but if a large distribution system was attacked, the problem of supplying water could be detrimental.”        
This report offers three primary countermeasures available to either overcome or reduce the potential introduction of CBR agents into water supplies:                “These countermeasures in order of priority are: (1) contamination avoidance, such as the use of protective barriers; (2) use of CBR agent detection, measurement, and identification instrumentation or methods; and (3) CBR agent treatment to minimize water distribution disruption, such as removal by filtration and disinfectant techniques. These priorities are established to reflect the greatest potential return in terms of operational effectiveness, and conservation of resources and manpower. That is, (emphasis added) the greatest benefit by far will be achieved by using contamination avoidance techniques and procedures in advance of an expected attack and subsequent to an attack.”        
As described below, the present invention uses a protective barrier approach, thus clearly satisfying the report's preferred countermeasure approach of “contamination avoidance.”
As noted in U.S. Utility patent application Ser. No. 11/810,946, for “Backflow Preventer Insert Valve,” filed Jun. 6, 2007 and published as US 2008/0029161, backflow preventers are used to prevent contamination of a building and/or public water distribution system by reducing or eliminating backflow of a contaminated hazardous fluid into such system(s). Conventional backflow preventers are mechanically sophisticated devices, that are threaded for pipes, unthreaded for tubing, or flanged at each end so that they can be installed, i.e., spliced, into a given piping system. Conventional backflow preventers require periodic inspection, testing, maintenance and repair. Therefore, needing to be visible and accessible, they are not tamper resistant. Thus, a conventional backflow preventer is generally installed in a source pipeline between a main municipal water supply line and a service line that feeds an installation such as, a hospital, industrial building, commercial establishment, multiple or single family residence. Moreover, a conventional backflow prevention valve typically includes two check valves that are configured to permit fluid flow in one direction, such as from a main municipal water supply distribution system to a particular building's service line. They are costly and labor intensive to install. Conventional backflow preventers are commonly used in buildings equipped with chemical processing equipment, sprinkler systems, etc. Backflow preventers are required by applicable plumbing codes, under specific conditions, to protect a building's potable water supply from accidental contamination so as to prevent a hazardous condition from materializing, which can occur from cross connection and flow reversal in a branch or pipe riser, due to a process or system malfunction. Left unchecked, hydraulic reversal can compromise the quality and safety of a building's potable water supply system and, potentially, the municipal water supply distribution system as well.
Historically, a typical backflow preventer valve consisted of a mechanical single spring-loaded check valve in a water supply line, generally placed between a pair of gate-type shutoff valves. Current building codes however, now require backflow preventers to include a pair of independently spring-loaded positive check valves. The motivation behind such a rule is that should one of the check valves fail, the second valve serves as a backup. Because of their mechanical complexity, current plumbing codes typically require that the check valve(s) be replaceable and repairable while on-line, i.e., without shutting down the system. However at the same time current plumbing codes for commercial, industrial, multi-story residential buildings and single homes do not require the installation of backflow preventers at every point of use. This leaves such buildings' internal drinking water supply vulnerable to injection of a toxic chemical, radiological or biological contaminant into the building's water supply system, with the added possibility of contaminating the municipal water supply distribution system in the process. Were the latter to occur, the water quality of an entire regional water distribution grid could be affected. Measures are needed to address this critical gap in security.
As noted, municipal codes generally require the replacement of single check valves with a double check valve backflow preventer. However, simply requiring building owners to undertake major re-plumbing and install these backflow preventers between the municipal water service distribution lines located in the street and downstream of the building's water meter does not address a given building's vulnerability to intentional contamination from within. Retrofitting a conventional backflow preventer to protect a building's internal potable water distribution system from possible intentional contamination at every point-of-use water supply terminus, such as, for example, by installing shutoff valves for all kitchen and bathroom fixtures, drinking fountains, hose bibs, etc., can be very expensive. First, each existing supply line would have to be re-plumbed to provide space to accommodate a conventional check valve assembly. Second, access for repair and replacement would be required for the maintenance of each such backflow preventer, since, as noted, these devices tend to be mechanically complex. Even in new construction, installation of conventional back flow preventers for each point-of-use fixture would be costly.
In the Jun. 18, 2004 article Cross Connection Control Programs And Backflow Preventers Are Essential Components of Safe Drinking Water Systems, published on the website backflowpreventiontechzone (at URL http://www. Backflowpreventiontechzone.com), it was noted that plumbing system cross connections between (i) potable and (ii) non-potable water supplies, water using equipment, and drainage systems, continue to be a serious global potential public health hazard. Wherever people congregate and use communal water supplies, water using equipment, and drainage systems, the danger of un-protected cross connections continues to threaten public health. Thus, there is a widening recognition that properly installed, maintained, and tested backflow prevention devices are critical elements of safe drinking water systems in homes, communities and workplaces. The report further noted that while backflow preventer device development began to accelerate and diversify beyond simple check valves in the mid-20th century, potable (“city”) water piping systems and water using equipment, especially as found inside industrial and medical buildings, have grown exponentially in complexity and are also continuously altered. Surveys over the past decades have shown that water using devices and equipment which can potentially contaminate a drinking water system continue to be connected to potable waterlines without properly selected, permitted, installed, maintained, and, if appropriate for the device, tested and certified, backflow preventer valves. Thus, “despite decades of new public health and occupational safety laws, as well as updated and revised plumbing codes, along with new improved backflow preventer devices, the cross connection problem continues to be an ongoing dynamic one.”
The backflowprevetiontechzone report further noted that recent cross connection inspection surveys (USC/FCCCHR) continue to reveal that the most prevalent and potentially hazardous potable water plumbing cross connection is the common hose connection (or hose bib) (UF/IFAS, 3/95), which is found in virtually every home and building. The predominant cause for such cross connection, known as backsiphonage, is the sudden and significant loss of hydraulic pressure in the water main. Excessive drops in water pressure have historically been attributed to, for example (i) a broken water main, (ii) a nearby fire where the Fire Department is using large quantities of water, or (iii) a water company official opening a fire hydrant to test it. Buildings located near a municipal water main break or an open fire hydrant will thus experience a lowering of water pressure and possibly backsiphonage.
A recent GAO-04-29 report to the United States Senate Committee on Environment specifically referenced fire hydrants as a top vulnerability, saying “[m]oreover, as recently reported by the American Water Works Association on May 2, 2007, terror training manuals found in Afghanistan showed plans to contaminate America's water supply.”
As noted above, hydrant security is currently relatively vulnerable to breach by a cunning terrorist. Using a tanker truck or pool, either at or relatively close to a hydrant, a toxic contaminant can be easily injected into the hydrant, and thus, the relevant regional water supply distribution system. All that is required is a hose connected to a hydrant discharge port and a pump having sufficient operating pressure to overcome the fluid pressure at the hydrant. Though more challenging, a hydrant's dry barrel discharge holes could also be turned into a water system entry point by using a specially tailored outside saddle valve.
It is noted that in areas known to be subjected to freezing temperatures, only a portion of the hydrant is above ground. Thus, in such hydrants, the main shut-off valve must be located below grade (ground level), immediately below the frost line. Such a main shut-off valve is generally connected using a vertical shaft above-ground mechanism, where a valve shaft (stem) with a break-away coupling extends from the main valve up through a seal at the top (bonnet) of the hydrant, where it can be operated with the proper tool. This design is known as a “dry barrel” hydrant, in that the barrel, or cylindrical body cavity of the hydrant, is normally dry. In a dry barrel hydrant, a drain valve located underground, at the bottom of the barrel housing, opens when the hydrant's main water valve is completely closed, thus allowing any water in upper section of the hydrant's body to automatically drain to the surrounding soil. This feature prevents the upper barrel of the hydrant from freezing, which can cause structural damage to, and/or breaking of, the hydrant.
In warmer areas, hydrants can be used with one or more valves in the above-ground portion. Unlike cold-weather hydrants, it is possible to turn the water supply on and off to each port. This style of hydrant is known as a “wet barrel” hydrant.
Both wet and dry barrel hydrants generally have multiple outlets. Wet barrel hydrant outlets are typically individually controlled, whereas a single stem simultaneously operates all of the outlets of a dry-barrel hydrant. Thus, wet barrel hydrants allow single outlets to be individually opened. A typical U.S. dry-barrel hydrant has two smaller outlets and one larger outlet.
Differential pressure reversals at a given fire hydrant can be attributed to many things. For example, vandals, or a fire located remotely where the demand for water adversely affects the pressure at other locations in the water supply distribution system.
Given the vulnerability of fire hydrants, and thus the entire regional potable water system to which they are connected, an improved and more secure fire hydrant with an integrated flow control/backflow preventer valve is truly needed.
What is further needed in the art is a fire hydrant backflow preventer valve that is economical to manufacture and maintain, essentially maintenance-free and tamper resistant.